Segmented inner stator and brushless permanent magnet motor with the same

Abstract

A segmented inner stator comprises a stator core and a stator winding. The stator core includes a plurality of core segments which are retained together in a circular arrangement by at least one retaining ring and are mated with each other. At least some of the core segments are provided with slots on the radial side surfaces. The at least one retaining ring comprises a radial extension portion extending along the axial side surface of the core segment. A plurality of corresponding axial projections are provided on the radial extension portion of the at least one retaining ring along the circumferential direction to be inserted into the slot on one of the core segments so that the core segments are not free to move axially and radially relative to each other or relative to the retaining rings.

1. A segmented inner stator for a brushless permanent magnet motor, the segmented inner stator comprising a stator core having a plurality of radially-extending poles separated by spaces, each of said poles being adapted for receiving a stator winding thereon, said stator core including a plurality of core segments which are mated and retained together in a circular arrangement by at least one retaining ring, wherein each of at least some of the core segments has an opening on an axially-facing surface, the retaining ring having a radial extension extending along the axially-facing surface of the core segments and a plurality of axial projections extending from the radial extension of the retaining rings into at least some of the openings in the core segments so that the core segments are retained axially and radially relative to each other and relative to the retaining ring, said spaces between the poles being substantially free of said axial projections. 
     
     
       2. The segmented inner stator for a brushless permanent magnet motor according to  claim 1  wherein each of at least some of the core segments is provided with a hole on the axially-facing surface, the radial extension portion of the retaining ring includes a plurality of holes, each of which is generally aligned with a hole in at least one of the core segments, and the stator further comprises a fastener mounted in at least one of the holes in the retaining ring and at least one hole in one of the core segments. 
     
     
       3. The segmented inner stator for a brushless permanent magnet motor according to  claim 1 , wherein the stator comprises two retaining rings which are assembled from opposite axial sides of the core segments to retain the plurality of core segments. 
     
     
       4. The segmented inner stator for a brushless permanent magnet motor according to  claim 2 , wherein the holes in the core segments form at least a portion of said openings on the axially-facing surfaces of the core segments. 
     
     
       5. The segmented inner stator for a brushless permanent magnet motor according to  claim 4 , wherein each of said openings in the core segments comprises a slot, and the plurality of axial projections on the radial extension portion of the at least one retaining ring are disposed in alternating slots. 
     
     
       6. The segmented inner stator for a brushless permanent magnet motor according to  claim 2 , wherein the inner stator is provided with a hub onto which the core segments and retaining ring are secured by the fastener. 
     
     
       7. The segmented inner stator for a brushless permanent magnet motor according to  claim 1 , wherein each of the core segments comprises a projection and a concave notch on opposite circumferentially-facing surfaces for engaging with the adjacent core segments. 
     
     
       8. The segmented inner stator for a brushless permanent magnet motor according to  claim 3 , wherein each of the retaining rings comprises an axial extension portion extending along radially inward-facing surfaces of the core segments, said axial extension portions being engaged with each other. 
     
     
       9. The segmented inner stator for a brushless permanent magnet motor according to  claim 1 , wherein the number of core segments is equal to the number of stator openings. 
     
     
       10. The segmented inner stator for a brushless permanent magnet motor according to  claim 9 , wherein the number of the core segments is 24. 
     
     
       11. A brushless permanent magnet motor equipped with the segmented inner stator according to  claim 1 . 
     
     
       12. The segmented inner stator for a brushless permanent magnet motor as set forth in  claim 1 , wherein each of the openings in the core segments is substantially radially aligned with a respective one of the poles. 
     
     
       13. A segmented inner stator for a brushless permanent magnet motor, the segmented inner stator comprising a stator core having a plurality of radially-extending poles separated by spaces, each of said poles being adapted for receiving a stator winding thereon, said stator core including a plurality of core segments which are mated and retained together in a circular arrangement by at least one retaining ring, wherein each of at least some of the core segments has an opening on an axially-facing surface, said opening being substantially radially aligned with a respective one of the poles, the retaining ring having a radial extension extending along the axially-facing surface of the core segment and a plurality of axial projections extending from the radial extension of the retaining rings into at least some of the openings in the core segments so that the core segments are retained axially and radially relative to each other and relative to the retaining rings. 
     
     
       14. The segmented inner stator for a brushless permanent magnet motor according to  claim 13  wherein each of at least some of the core segments is provided with a hole on the axially-facing surface, the radial extension portion of the retaining ring includes a plurality of holes, each of which is generally aligned with a hole in one of the core segments, and the stator further comprises a fastener mounted in one of the holes in the retaining ring and a corresponding hole in one of the core segments. 
     
     
       15. The segmented inner stator for a brushless permanent magnet motor according to  claim 14 , wherein the holes in the core segments form at least a portion of said openings on the axially-facing surfaces of the core segments. 
     
     
       16. The segmented inner stator for a brushless permanent magnet motor according to  claim 15 , wherein each of said openings in the core segments comprises a slot, and the plurality of axial projections on the radial extension portion of the at least one retaining ring are disposed in alternating slots. 
     
     
       17. The segmented inner stator for a brushless permanent magnet motor according to  claim 14 , wherein the inner stator is provided with a hub onto which the core segments and retaining ring are secured by the fastener. 
     
     
       18. The segmented inner stator for a brushless permanent magnet motor according to  claim 13 , wherein the stator comprises two retaining rings which are assembled from opposite axial sides of the core segments to retain the plurality of core segments. 
     
     
       19. The segmented inner stator for a brushless permanent magnet motor according to  claim 18 , wherein each of the retaining rings comprises an axial extension portion extending along the radial inner surface of the core segments, each of said axial extension portions being engaged with another axial extension portion. 
     
     
       20. The segmented inner stator for a brushless permanent magnet motor according to  claim 13 , wherein each of the core segments comprises a projection and a concave notch on opposite circumferentially-facing surfaces for engaging the adjacent core segments. 
     
     
       21. The segmented inner stator for a brushless permanent magnet motor according to  claim 13 , wherein the number of core segments is equal to the number of stator openings. 
     
     
       22. A brushless permanent magnet motor equipped with the segmented inner stator according to  claim 13 . 
     
     
       23. The segmented inner stator for a brushless permanent magnet motor according to  claim 1 , wherein said openings in the core segments and the axial projections of the retaining ring are positioned radially inward from the poles. 
     
     
       24. The segmented inner stator for a brushless permanent magnet motor according to  claim 13 , wherein said openings in the core segments and the axial projections of the retaining ring are positioned radially inward from the poles.